2. Changes in bacterial traits Caused by: Changes in environmental conditions (only phenotypic changes) Changes in the genetic codes 1- Intermicrobial exchange 2- Mutations (point mutations, insertions, deletions)

3. Intermicrobial exchange Transformation (Capturing DNA from solution) Transduction (Phage-mediated) Conjugation (Bacterial Sex)

4. Original Transformation Exp. F. Griffith (1928) using pneumococci

5. DNA-Mediated Transformation

7. Intermicrobial exchanges by vectors

8. 8 Characteristics of genetic vectors must be capable of carrying a significant piece of donor DNA must be readily accepted by the host plasmids – small, well characterized, easy to manipulate & can be transferred into appropriate host cells through transformation bacteriophages – have the natural ability to inject their DNA into bacterial hosts through transduction

9. Transduction (madiated by phage)

11. Lytic versus Lysogenic

12. Generalized Transduction

14. Transduction Types of transduction  Generalized - Transduction in which potentially any dornor bacterial gene can be transferred.  Specialized (Restricted): Transduction in which only certain donor genes can be transferred.

15. Restricted Transduction (Lysogenic Phage) gal bio gal bio gal bio gal bio gal

16. Transduction Definition Types of transduction Significance  Common in Gram+ bacteria  Lysogenic (phage) conversion e.g. Corynebacterium diptheriae toxin Toxin derived from lysogenic phage

17. Conjugation

18. Conjugation Definition: Gene transfer from a donor to a recipient by direct physical contact between cells Mating types in bacteria  Donor F factor (Fertility factor)  F (sex) pilus Donor Recipient  Recipient Lacks an F factor

19. Conjugation Significance  Gram - bacteria Antibiotic resistance  Gram + bacteria Production of adhesive material by donor cells

20. Conjugation

21. Conjugation: Sex or F Pilus

22. Plasmids

23. Plasmids Definition: Extrachromosomal genetic elements that are capable of autonomous replication (replicon) Plasmid Types: Congugative & Non-congugative Congugative & Non-congugative Episome - a plasmid that can integrate into the chromosome Casmid – An integration of a plasmid and a bacteriophage

24. Phenotypic effects Fertility (F factor) Bacteriocinogenic (or encoding some other toxins) Resistance (R factors)

25. Structure of R Factors RTF  Conjugative plasmid  Transfer genes Tn 9 Tn 21 Tn 10 Tn 8 RTF R determinant  Resistance genes

26. Self-Transmissible R Plasmid

27. Conjugation: F Plasmid Transfer

28. F + and HFr cells Integrated (Hfr) (High Frequency of Recombination) F+F+ Hfr

29. Hfr and F’ cells Hfr F’

30. Mechanism of Hfr x F - Crosses HfrF-F- F-F- F-F- F-F-

32. Mechanism of F’ x F - Crosses F’ F-F- F-F-

33. Transposable Genetic Elements Definition: Segments of DNA that are able to move from one location to another (across the genome or from one genome to another) Properties  “Random” movement Transposase  Transposition may be accompanied by duplication

34. Types of Transposable Genetic Elements Transposons (Tn)/ Insertion elements (IS)  Definition: Elements that carry other genes in addition to those involved in transposition  Nomenclature - Tn10, IS6110  Structure Composite Tns  Importance Antibiotic resistance Epidemiology and evolutionary studies IS Resistance Gene(s) IS Resistance Gene(s)